1. Field of the Invention
The present invention generally relates to printed circuit board apparatus, and more particularly relates to connector apparatus used to operatively couple flexible ribbon cables to printed circuit boards in, for example, computers.
2. Description of Related Art
In computer applications, as well as a variety of other applications, it is often necessary to connect one or more flexible ribbon cables to a printed circuit board in order to transmit electrical signals to and/or receive electrical signals from the printed circuitry on the board. A flexible ribbon cable is typically formed from a flexible, electrically insulative film material, such as mylar, having a spaced series of electrically conductive traces formed on a side surface thereof. Under conventional practice, these traces are customarily coupled to corresponding traces on a side surface of a rigid circuit board using one of two types of connector structures--a "zero insertion force" connector or a "low insertion force" connector.
Using the zero insertion force connector, the board connection end of the flexible ribbon cable is slipped into a slot formed in a removable connector body which is then mated with a corresponding connector structure fixedly secured to a side of the rigid circuit board and operatively connected to its surface trace circuitry. The mating of the removable connector body with its associated fixed connector structure closes the connector body slot in a manner clamping the board connection end of the flexible ribbon cable therein and operatively coupling the ribbon cable to the circuit board. Subsequent disconnection of the ribbon cable from the circuit board is achieved by disconnecting the removable connector body from its associated fixed connector structure. This automatically causes the connector body slot to widen, thereby unclamping the ribbon cable connector end and permitting it to be slipped out of the connector body slot.
In the low insertion force connector the board connection end of the ribbon cable is manually plugged into a suitable slot-shaped socket formed in a connector structure mounted on the circuit board. Insertion of the board connection end of the ribbon cable into this slot slidably and removably engages electrically conductive surface traces on the ribbon end with corresponding contact portions within the connector structure. Subsequent disconnection of the PG,4 ribbon cable from the circuit board is achieved simply by pulling the ribbon cable connector end out of the connector structure slot.
Both of these conventional ribbon cable connector structures are subject to a variety of well known problems, limitations and disadvantages. For example, over time and repeated connections and disconnection of the ribbon cable thereto, they each tend to undesirably crease and crack the surface traces on the board connector end of the ribbon cable. Additionally, the low insertion force connector structure tends, through friction, to at least partially wipe away end portions of the cable surface traces after repeated insertions therein and removal therefrom of the board connector end of the ribbon cable.
In addition to potentially damaging end portions of the ribbon cable which they couple to their associated circuit board, these conventional ribbon cable connector structures have a tendency to create undesirable misalignments between their internal contact areas and the traces on the received ribbon cable connector end due to the manufaturing process variations when the cable is printed and cut. Moreover, these types of connector structures are typically manufactured only with an industry standard pitch spacing of, for example, 1 mm, 0.100", etc. Accordingly, the board connection end of a given ribbon cable to be used with one of these conventional connector structures must have, as to its surface traces, an identical pitch spacing. An often desirable larger pitch spacing in the ribbon cable board connection end, which would tend to lessen potential misalignment problems, typically cannot be accommodated by these conventional types of connector structures.
It can be readily be seen from the foregoing that it would be highly desirable to provide improved apparatus for coupling flexible cables to printed circuit boards in a manner eliminating or at least substantially reducing the above-mentioned problems, limitations and disadvantages associated with conventional connector structures of the type generally described above. It is accordingly an object of the present invention to provide such improved apparatus.